<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    li {
      width: 100px;
      height: 100px;
      opacity: 0.5;
    }
    li:first-child {
      background-color: burlywood;
    }
    li:nth-child(2) {
      background-color: brown;
    }
    li:nth-child(3) {
      background-color: chocolate;
    }
    li:nth-child(4) {
      background-color: crimson;
    }
    li:nth-child(5) {
      background-color: darkviolet;
    }
    li:last-child {
      background-color: orangered;
    }
    .cls {
      color: blue;
      font-size: 32px;
    }
  </style>
  <script src="../../JavaScript/jQuery.js"></script>
  <script>
    $(function () {
      $('ul>li').mouseenter(function () {
        $(this).css('opacity', 1).siblings().css('opacity','0.5');
        $('ul>li').attr('class','cls');
      }).mouseout(function () {
        $(this).css('opacity', '0.5');
        $('ul>li').attr('class','');
      }).click(function () {
        alert('123');
      });
    });
  </script>
</head>
<body>
  <ul>
    <li>岳</li>
    <li>婷</li>
    <li>婷</li>
    <li>董</li>
    <li>喜</li>
    <li>炜</li>
  </ul>
</body>
</html>